1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* L2TPv3 ethernet pseudowire driver
3 *
4 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
5 */
6
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9 #include <linux/module.h>
10 #include <linux/skbuff.h>
11 #include <linux/socket.h>
12 #include <linux/hash.h>
13 #include <linux/l2tp.h>
14 #include <linux/in.h>
15 #include <linux/etherdevice.h>
16 #include <linux/spinlock.h>
17 #include <net/sock.h>
18 #include <net/ip.h>
19 #include <net/icmp.h>
20 #include <net/udp.h>
21 #include <net/inet_common.h>
22 #include <net/inet_hashtables.h>
23 #include <net/tcp_states.h>
24 #include <net/protocol.h>
25 #include <net/xfrm.h>
26 #include <net/net_namespace.h>
27 #include <net/netns/generic.h>
28 #include <linux/ip.h>
29 #include <linux/ipv6.h>
30 #include <linux/udp.h>
31
32 #include "l2tp_core.h"
33
34 /* Default device name. May be overridden by name specified by user */
35 #define L2TP_ETH_DEV_NAME "l2tpeth%d"
36
37 /* via netdev_priv() */
38 struct l2tp_eth {
39 struct l2tp_session *session;
40 atomic_long_t tx_bytes;
41 atomic_long_t tx_packets;
42 atomic_long_t tx_dropped;
43 atomic_long_t rx_bytes;
44 atomic_long_t rx_packets;
45 atomic_long_t rx_errors;
46 };
47
48 /* via l2tp_session_priv() */
49 struct l2tp_eth_sess {
50 struct net_device __rcu *dev;
51 };
52
l2tp_eth_dev_init(struct net_device * dev)53 static int l2tp_eth_dev_init(struct net_device *dev)
54 {
55 eth_hw_addr_random(dev);
56 eth_broadcast_addr(dev->broadcast);
57 netdev_lockdep_set_classes(dev);
58
59 return 0;
60 }
61
l2tp_eth_dev_uninit(struct net_device * dev)62 static void l2tp_eth_dev_uninit(struct net_device *dev)
63 {
64 struct l2tp_eth *priv = netdev_priv(dev);
65 struct l2tp_eth_sess *spriv;
66
67 spriv = l2tp_session_priv(priv->session);
68 RCU_INIT_POINTER(spriv->dev, NULL);
69 /* No need for synchronize_net() here. We're called by
70 * unregister_netdev*(), which does the synchronisation for us.
71 */
72 }
73
l2tp_eth_dev_xmit(struct sk_buff * skb,struct net_device * dev)74 static netdev_tx_t l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
75 {
76 struct l2tp_eth *priv = netdev_priv(dev);
77 struct l2tp_session *session = priv->session;
78 unsigned int len = skb->len;
79 int ret = l2tp_xmit_skb(session, skb);
80
81 if (likely(ret == NET_XMIT_SUCCESS)) {
82 atomic_long_add(len, &priv->tx_bytes);
83 atomic_long_inc(&priv->tx_packets);
84 } else {
85 atomic_long_inc(&priv->tx_dropped);
86 }
87 return NETDEV_TX_OK;
88 }
89
l2tp_eth_get_stats64(struct net_device * dev,struct rtnl_link_stats64 * stats)90 static void l2tp_eth_get_stats64(struct net_device *dev,
91 struct rtnl_link_stats64 *stats)
92 {
93 struct l2tp_eth *priv = netdev_priv(dev);
94
95 stats->tx_bytes = (unsigned long)atomic_long_read(&priv->tx_bytes);
96 stats->tx_packets = (unsigned long)atomic_long_read(&priv->tx_packets);
97 stats->tx_dropped = (unsigned long)atomic_long_read(&priv->tx_dropped);
98 stats->rx_bytes = (unsigned long)atomic_long_read(&priv->rx_bytes);
99 stats->rx_packets = (unsigned long)atomic_long_read(&priv->rx_packets);
100 stats->rx_errors = (unsigned long)atomic_long_read(&priv->rx_errors);
101 }
102
103 static const struct net_device_ops l2tp_eth_netdev_ops = {
104 .ndo_init = l2tp_eth_dev_init,
105 .ndo_uninit = l2tp_eth_dev_uninit,
106 .ndo_start_xmit = l2tp_eth_dev_xmit,
107 .ndo_get_stats64 = l2tp_eth_get_stats64,
108 .ndo_set_mac_address = eth_mac_addr,
109 };
110
111 static struct device_type l2tpeth_type = {
112 .name = "l2tpeth",
113 };
114
l2tp_eth_dev_setup(struct net_device * dev)115 static void l2tp_eth_dev_setup(struct net_device *dev)
116 {
117 SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
118 ether_setup(dev);
119 dev->priv_flags &= ~IFF_TX_SKB_SHARING;
120 dev->features |= NETIF_F_LLTX;
121 dev->netdev_ops = &l2tp_eth_netdev_ops;
122 dev->needs_free_netdev = true;
123 }
124
l2tp_eth_dev_recv(struct l2tp_session * session,struct sk_buff * skb,int data_len)125 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
126 {
127 struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
128 struct net_device *dev;
129 struct l2tp_eth *priv;
130
131 if (!pskb_may_pull(skb, ETH_HLEN))
132 goto error;
133
134 secpath_reset(skb);
135
136 /* checksums verified by L2TP */
137 skb->ip_summed = CHECKSUM_NONE;
138
139 /* drop outer flow-hash */
140 skb_clear_hash(skb);
141
142 skb_dst_drop(skb);
143 nf_reset_ct(skb);
144
145 rcu_read_lock();
146 dev = rcu_dereference(spriv->dev);
147 if (!dev)
148 goto error_rcu;
149
150 priv = netdev_priv(dev);
151 if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
152 atomic_long_inc(&priv->rx_packets);
153 atomic_long_add(data_len, &priv->rx_bytes);
154 } else {
155 atomic_long_inc(&priv->rx_errors);
156 }
157 rcu_read_unlock();
158
159 return;
160
161 error_rcu:
162 rcu_read_unlock();
163 error:
164 kfree_skb(skb);
165 }
166
l2tp_eth_delete(struct l2tp_session * session)167 static void l2tp_eth_delete(struct l2tp_session *session)
168 {
169 struct l2tp_eth_sess *spriv;
170 struct net_device *dev;
171
172 if (session) {
173 spriv = l2tp_session_priv(session);
174
175 rtnl_lock();
176 dev = rtnl_dereference(spriv->dev);
177 if (dev) {
178 unregister_netdevice(dev);
179 rtnl_unlock();
180 module_put(THIS_MODULE);
181 } else {
182 rtnl_unlock();
183 }
184 }
185 }
186
l2tp_eth_show(struct seq_file * m,void * arg)187 static void l2tp_eth_show(struct seq_file *m, void *arg)
188 {
189 struct l2tp_session *session = arg;
190 struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
191 struct net_device *dev;
192
193 rcu_read_lock();
194 dev = rcu_dereference(spriv->dev);
195 if (!dev) {
196 rcu_read_unlock();
197 return;
198 }
199 dev_hold(dev);
200 rcu_read_unlock();
201
202 seq_printf(m, " interface %s\n", dev->name);
203
204 dev_put(dev);
205 }
206
l2tp_eth_adjust_mtu(struct l2tp_tunnel * tunnel,struct l2tp_session * session,struct net_device * dev)207 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
208 struct l2tp_session *session,
209 struct net_device *dev)
210 {
211 unsigned int overhead = 0;
212 u32 l3_overhead = 0;
213 u32 mtu;
214
215 /* if the encap is UDP, account for UDP header size */
216 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
217 overhead += sizeof(struct udphdr);
218 dev->needed_headroom += sizeof(struct udphdr);
219 }
220
221 lock_sock(tunnel->sock);
222 l3_overhead = kernel_sock_ip_overhead(tunnel->sock);
223 release_sock(tunnel->sock);
224
225 if (l3_overhead == 0) {
226 /* L3 Overhead couldn't be identified, this could be
227 * because tunnel->sock was NULL or the socket's
228 * address family was not IPv4 or IPv6,
229 * dev mtu stays at 1500.
230 */
231 return;
232 }
233 /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
234 * UDP overhead, if any, was already factored in above.
235 */
236 overhead += session->hdr_len + ETH_HLEN + l3_overhead;
237
238 mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead;
239 if (mtu < dev->min_mtu || mtu > dev->max_mtu)
240 dev->mtu = ETH_DATA_LEN - overhead;
241 else
242 dev->mtu = mtu;
243
244 dev->needed_headroom += session->hdr_len;
245 }
246
l2tp_eth_create(struct net * net,struct l2tp_tunnel * tunnel,u32 session_id,u32 peer_session_id,struct l2tp_session_cfg * cfg)247 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
248 u32 session_id, u32 peer_session_id,
249 struct l2tp_session_cfg *cfg)
250 {
251 unsigned char name_assign_type;
252 struct net_device *dev;
253 char name[IFNAMSIZ];
254 struct l2tp_session *session;
255 struct l2tp_eth *priv;
256 struct l2tp_eth_sess *spriv;
257 int rc;
258
259 if (cfg->ifname) {
260 strscpy(name, cfg->ifname, IFNAMSIZ);
261 name_assign_type = NET_NAME_USER;
262 } else {
263 strcpy(name, L2TP_ETH_DEV_NAME);
264 name_assign_type = NET_NAME_ENUM;
265 }
266
267 session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
268 peer_session_id, cfg);
269 if (IS_ERR(session)) {
270 rc = PTR_ERR(session);
271 goto err;
272 }
273
274 dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
275 l2tp_eth_dev_setup);
276 if (!dev) {
277 rc = -ENOMEM;
278 goto err_sess;
279 }
280
281 dev_net_set(dev, net);
282 dev->min_mtu = 0;
283 dev->max_mtu = ETH_MAX_MTU;
284 l2tp_eth_adjust_mtu(tunnel, session, dev);
285
286 priv = netdev_priv(dev);
287 priv->session = session;
288
289 session->recv_skb = l2tp_eth_dev_recv;
290 session->session_close = l2tp_eth_delete;
291 if (IS_ENABLED(CONFIG_L2TP_DEBUGFS))
292 session->show = l2tp_eth_show;
293
294 spriv = l2tp_session_priv(session);
295
296 l2tp_session_inc_refcount(session);
297
298 rtnl_lock();
299
300 /* Register both device and session while holding the rtnl lock. This
301 * ensures that l2tp_eth_delete() will see that there's a device to
302 * unregister, even if it happened to run before we assign spriv->dev.
303 */
304 rc = l2tp_session_register(session, tunnel);
305 if (rc < 0) {
306 rtnl_unlock();
307 goto err_sess_dev;
308 }
309
310 rc = register_netdevice(dev);
311 if (rc < 0) {
312 rtnl_unlock();
313 l2tp_session_delete(session);
314 l2tp_session_dec_refcount(session);
315 free_netdev(dev);
316
317 return rc;
318 }
319
320 strscpy(session->ifname, dev->name, IFNAMSIZ);
321 rcu_assign_pointer(spriv->dev, dev);
322
323 rtnl_unlock();
324
325 l2tp_session_dec_refcount(session);
326
327 __module_get(THIS_MODULE);
328
329 return 0;
330
331 err_sess_dev:
332 l2tp_session_dec_refcount(session);
333 free_netdev(dev);
334 err_sess:
335 kfree(session);
336 err:
337 return rc;
338 }
339
340 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
341 .session_create = l2tp_eth_create,
342 .session_delete = l2tp_session_delete,
343 };
344
l2tp_eth_init(void)345 static int __init l2tp_eth_init(void)
346 {
347 int err = 0;
348
349 err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
350 if (err)
351 goto err;
352
353 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n");
354
355 return 0;
356
357 err:
358 return err;
359 }
360
l2tp_eth_exit(void)361 static void __exit l2tp_eth_exit(void)
362 {
363 l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
364 }
365
366 module_init(l2tp_eth_init);
367 module_exit(l2tp_eth_exit);
368
369 MODULE_LICENSE("GPL");
370 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
371 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
372 MODULE_VERSION("1.0");
373 MODULE_ALIAS_L2TP_PWTYPE(5);
374